The Royal Collection’s biggest money-spinner was Windsor Castle, which is open all year round and generated £14m in ticket sales and £3.3m in sales in its shop.

Other income comes from visitors to The Queen’s Gallery at Buckingham Palace, The Royal Mews and the Palace of Holyroodhouse in Edinburgh.

Jonathan Marsden, director of the Royal Collection, said: “The marriage of The Duke and Duchess of Cambridge in April 2011 provided the best possible start to the year.

“The early success of the special commemorative range of china from the time of its launch the previous December was repeated during the summer, when unprecedented numbers came to see the Duchess’s wedding dress.”

The Prince of Wales, the chairman of the Royal Collection Trust, said it gave him “great satisfaction” that the Queen’s art works “can continue to be managed to such a high standard without placing any burden on the public funds”.